The present invention is generally related to utilization of sealing current on Digital Subscriber Lines (DSL) without Plain Old Telephony Service (POTS) to test metallic line integrity and, more specifically, to an autonomous metallic supervision with sealing current of DSL lines without underlying POTS.
With the increase in use of cellular phones and Voice over Internet Protocol (VoIP), many residences and other users are discontinuing their use of POTS. DSL was initially created to be used in conjunction with POTS, where POTS utilized the frequency band below 4 Kilo Hertz (KHz) and DSL utilized the frequency band above 4 kHz. POTS utilizes a sealing or wetting current which is a direct current injected into a line to prevent galvanic corrosion of metallic (copper) lines and to prevent oxidation at splices. With the switch by residences to utilize DSL without underlying POTS, the benefits of the sealing or wetting current built into POTS is no longer present. Such a use of DSL without underlying POTS is referred to as dry DSL as there is no wetting current injected into the line.
Therefore, what is needed is dry DSL metallic connectivity testing with sealing current. More specifically, what is needed is autonomous metallic supervision with sealing current of DSL lines without underlying POTS that overcomes the limitations described above. The present invention injects a wetting (sealing) current into dry DSL lines to allow measurement of Direct Current (DC) loop resistances and to provide the benefits of corrosion and oxidation resistance previously only enjoyed from utilizing POTS. The measurement of DC loop resistance allows insight into metallic connectivity integrity of the dry DSL connection.